Scientists have discovered traces of fungi lurking in the tumors of people with different types of cancer, including breast, colon, pancreatic and lung cancers.
However, it is not yet clear that these fungi play any role in the development or progression of cancer.
Two new studies, published September 29 in the journal Cellrevealed DNA from fungal cells hidden in tumors throughout the body.
In one study, researchers dusted off fungal genetic fingerprints in 35 different types of cancer, examining more than 17,000 tissue, blood and plasma samples from cancer patients.
Not every tumor tissue sample tested positive for fungi, but overall, the team found fungi in all 35 types of cancer evaluated.
“Some tumors had no fungus at all, and some had a huge amount of fungus,” co-lead author Ravid Straussman, a cancer biologist at the Weizmann Institute of Science in Rehovot, Israel, told STAT. Often, however, when the tumors contained fungi, they did so in “low abundance,” the team noted in their report.
Based on the amount of fungal DNA his team uncovered, Straussman estimated that some tumors contain one fungal cell for every 1,000 to 10,000 cancer cells.
If you consider that a small tumor can be loaded with about a billion cancer cells, you can imagine that fungi can “have a big impact on cancer biology,” he said.
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Straussman and his team found that each type of cancer tended to be associated with its own unique collection of fungal species. These included typically harmless fungi known to live in humans and some that can cause disease, such as yeast infections.
In turn, these fungal species often coexisted with specific bacteria within the tumor. At present, it is unknown whether and how these microbes interact in the tumor and whether their interactions help fuel the spread of cancers.
The second Cell The study revealed similar results to the first, but focused specifically on gastrointestinal, lung and breast tumors, Nature mentionted. The researchers found that each of these three types of cancer tended to harbor the fungal genera Candida, Blastomycesand Malasseziarespectively.
Both research groups found evidence that the growth of certain fungi may be linked to worse cancer outcomes. For example, Straussman’s group found that breast cancer patients with the fungus Malassezia globosa their tumors showed worse survival rates than patients whose tumors did not have the fungus.
The second team, led by immunologist Iliyan Iliev at Weill Cornell Medicine in New York, found that patients with relatively high abundance Candida in their gastrointestinal tumors they showed increased gene activity linked to uncontrolled inflammation, cancer spread and low survival rates, Nature mentionted.
Despite these early hints, no study can definitively say whether the fungi actually drive these bad outcomes, or whether aggressive cancers simply create an environment where these fungi can easily grow.
The studies also do not address whether fungi can contribute to cancer development by pushing healthy cells to become cancerous.
Both studies have similar limitations. For example, they pulled tissue and blood samples from existing databases, and it’s possible that some samples were contaminated with fungi during the collection process, said Ami Bhatt, a microbiome specialist at Stanford University in California. Nature.
Both research teams tried to eliminate such contaminants, but even with these precautions, Bhatt said it would be best to repeat the results with samples taken in a sterile environment.
Straussman told STAT that these initial studies serve as a springboard for future research into mycobiota, the microbial communities associated with cancers.
“As a field, we need to evaluate everything we know about cancer,” he said. “Look at everything through the lens of the microbiome – bacteria, fungi, tumors, even viruses. There are all these creatures in the tumor and they have to have some effect.”
This article was originally published by Live Science. Read the original article here.